Vintage diamond brooch with "BB" in script diamond letters. Locking c shaped clasp, which is a bit stiff - also known as very secure :) Circa mid 20th century.

Diamonds: 22 total, single cut. They're small, under 0.15 carats together. At this size they are eye clean, though under magnification there are inclusions.
Not marked, tested as 9 carat gold throughout, which is white in colour.
Measures approx 32.3 mm / 1.27 inches in total length. BB is approx 13.8 mm wide by 11.4 mm tall.
Weighs 2.7 grams.